The Experiment
by Wintreaux
Summary: Amy gives Sheldon a serum that awakens his carnal side in hopes he focuses all his lust and attention the object of his desire: HER. Only...it's not her. - Sheldon/Penny - OOC -
1. I

**I. **_**Prologue**_

She was _tired_.

They've been dating for nearly three years now, and the absolute furthest she's ever gotten with him (in terms of intimacy) was a point second a kiss, when she tried to take a page out of Penny's book and bought him what she thought was a rare action figure. (_"Amy, Sheldon has this action figure already. You should've checked with me or the guys before you went and spent so much money..."_) She could still hear the sympathy in the blonde's voice as they watched Sheldon take the box from his girlfriend and bring it to his bedroom, probably to store it in his closet or something. No need for two of the same items to be on display, a waste of shelf space that was.

She's tried in vain since then to get him to notice her, sexually. She'd wear perfumes, or she'd wear skirts that were to her shin instead of her ankle. It was like everything she did, she was invisible to him. It was extremely off putting at how well he was at ignoring sexual advances. At this point, she felt like the only way to get through to him was to tie him down and jump his bones. Though, she figured that was wrong. Morally, of course. Still, the idea still bounced around the back of her mind.

What she found more ethical was the thought of using a serum she developed on her monkey's, to help wake up his more…_carnal_ desires. It wouldn't alter him or his personality (or it _shouldn't_), what it would do is just wake up the lust and need he felt inside of that he kept so well repressed. She expected the side effects to take a lesser toll on him than her monkey's, he was larger anyways. So, she didn't expect him to become animalistic. He would just be focused a lot more on her, than usual. The serum would make him lust for the object of his affection and love, the thing that drove him wild with need and sexual desire the most. _Her_.

She would sneak it into his drink while he wasn't looking and would catalogue his reaction as the days went on. She would pay close attention to him as the experiment went on and would write down his actions –this would be very good for her work, whether it succeeded or failed.

The eager brunette looked at the vial in her hand, it was a clear liquid that had no taste nor smell. It would virtually be undetectable, but still, she had to be careful while putting it into his drink. He was very particular about his food, and barely ever took his eyes off his plate. She doubled the dosage (because it had only worked on monkey's so far, who knew how much a human needed), and sealed the vial; she'd do it tonight. The serum needed a few hours to get into the system usually, so it would be best if he slept while it worked and tomorrow, she'd start collecting data.

She sighed deeply as she placed the glass vial carefully into a container and placed the container into her bag, she'd go to the guys apartment tonight for Halo night and slip it in then. She had no real hope that this would work, Sheldon was, as he called, Homo Novus; he had control over every aspect of his body and life. She was positive his body would find a way to reject this serum too.

* * *

"Take that!"

Penny shouted loudly, as she blew Raj up and a blood effect was shown on the Indian's screen. He groaned as he placed his remote down, waiting to respawn. Howard was still in the game, and if he managed to stay in the game by the time he respawned, they still had a chance against the evil team that was Sheldon and Penny. He never understood why they faced off against them every week, knowing the results would be the same, they'd lose exceptionally, and hang their heads in shame while Sheldon and Penny did a victory air fist pump.

Just then, the door opened, and a smiling Amy walked through the door. Everyone nodded their greeting, and she waved and smiled back, "Hey Bestie," she acknowledged the only female in the room. The blonde glanced up at Amy quickly, "Oh hey, Ames," she greeted, but she sounded as if she would say something else but paused. She assisted Sheldon in blowing Howard up and then looked back up at Amy, "Here, you can sit next to Sheldon, I'll get the floor."

She looked like she wanted to object, but still she remembered her plan and nodded, "Thanks, Bestie. I always love any elbow time I can get with my man," she grinned as she playfully bumped his elbow. Sheldon only regarded her quickly, with a stern look, before looking back at the screen.

"Please refrain from bumping my person, in any instance, especially this one. I know you're aware that I'm trying to destroy Team Raj and Howard in a vicious game of Halo, I cannot afford to lose because I was bumped off axis," he stated firmly, "Other than that, hello Amy."

She sighed deeply and took her bag off; she prayed this serum worked because if not she wasn't sure just how much she could take of this with Sheldon. Sure, she was comfortable and had a smart boyfriend, that was more than her mother would give her credit for, but she never expected to be lacking in the sexual department. No, she wasn't experienced, but neither was Sheldon. She knew they could learn together. She looked at Leonard who had been on his phone this entire time, ignoring the situation at hand. Maybe she could get tips on sexual intercourse from Penny, she had Leonard whipped around her finger and they weren't even dating. Hadn't been for a few years now.

She settled in, careful not to touch Sheldon, and watched the game with uninterested eyes. She didn't get Halo; she didn't get a lot of things the guys and Penny liked. First of all, she was surprised Penny even liked the same things as them (Well, some of the same things), she was also surprised a woman like Penny even spent time with them. Though, she decided it was never best to judge a book by its cover. That's what many teenage females and males did to her back in high school.

"Would you like a beverage, Sheldon?"

The man in question looked up at her quickly, before speaking, "Why yes, Amy, thank you for being so hospitable."

Amy smiled and stood to her feet, stepping over everyone and going to the kitchen. It didn't take her long to get a cup of water and pour the serum in discreetly. She was sure it was enough to last the week; she didn't know when she'd be able to sneak some more into his food, so she made sure to bring enough for one dose. She smelt the drink and nodded once she realized it had no smell. It was undetectable, like she thought.

She brought the glass to the man and watched as he drank it down without mercy. "Thank you, Amy, I was rather thirsty it seems."

All of a sudden, she felt giddy. Sheldon had drunk her serum, and he would soon start to turn his attention to her and be attracted to her the way she was to him. This was everything she wanted and more, and she couldn't wait for tomorrow. For now, she had to wait for him to go to bed so the serum could take its course naturally. She knew she couldn't stay around the apartment without causing a scene, due to her giddiness, so she said goodnight and left.

She'd check on him at work tomorrow, and if he kissed her or ravished her in his office…well that was just a bonus.


	2. II

**II.**

His concentration was broken when he heard a soft knock on his office door.

He sighed deeply before capping the dry erase marker and placing it back in its place, "Come in," he said impatiently.

The door to his office opened, and he was surprised to see Amy standing there. Though she was his girlfriend, they did agree to not bother each other while at work, in fear of distracting the other from their work and experiments. So, he was confused as to why she was currently walking into his office with a smile plastered to her face, he had never seen her smile like this before and it unnerved him. He wouldn't be lying if he said it reminded him of the Cheshire cat from that one movie he detested, but endured, because of a certain blonde neighbor.

He noticed she wore a blue turtle neck, and a brown wool skirt. It wasn't her average brown skirt that went to her ankles, this one came a few inches below her knee and showed off some of her pale legs. Her tube socks and black orthopedic shoes proudly on display. He sniffed the air slightly and was taken back when he noticed she was wearing perfume. He had noticed before she wore perfume occasionally, and it was usually when she tried to have coitus with him, he became nervous would she try this again? In his office?

"Hello, Sheldon," she sounded normal and he released a breath.

He nodded, "Amy, what brings you to my office?"

She walked over towards him slowly, like a lion taunting its prey. He was confused about the actions, but he let her continue whatever it was she thought she was doing, "I was just checking in on you, making sure you were alright…" she trailed off, and her voice went an octave deeper, "How do you feel?"

The scientist narrowed his eyes, "I feel adequate, Amy. I am not sick, and I just recently had a bowel movement, may I ask why the sudden interest in my health?"

She moved beside him, and he immediately tensed up as her chest brushed against his arm, "Just making sure you weren't getting too…hot," she whispered.

He quickly moved away from his girlfriend, "Oh that's just enough, Amy. I don't know what it is you're trying to do but I don't appreciate you blowing your saliva molecules into my ear. Nor do I appreciate you pressing your bosom onto my person, please…if that was it, I'd like to get back to my work," he pointed towards the door.

Amy frowned deeply, she doubled his dosage he should be affected, and he should be wanting to rip her clothes off her body. She knew he was a genius, but he couldn't possibly make his body fight off the serum, that was impossible. She sighed, a new determination in her eyes, she knew the serum would only get stronger as the days go by, and the only way he could fulfill his desire was to copulate with her. She was the object of his affection and desires anyways. Though, knowing this, she didn't want to take any chances. She'd dose him one more time, at lunch, he'd be on a triple dosage and that would _definitely_ get him going.

"Will you be needing a ride home?"

He shook his head, his back facing her, "Penny will be picking me up this evening."

She nodded, good, it would give her more time to research her data before going to the apartment for Pizza night.

* * *

It was August, and it was _hot_.

It wasn't as hot at the July heat they experienced, but damn she found herself not being able to contain her excitement at the possibility of cooler weather in September. Every inch of her body was sticking to her driver seat and although she showered not too long ago, she could feel the thin layer of sweat coating her body. She rolled her eyes at the broken AC in her car and got out of the death box. She perched up against the door and sighed, Dr. Whackadoodle better hurry up before she leaves him. The first time she was _on time_ and he decided to be late.

Just then the front doors opened, and some other scientists poured out of the building, some stopped to look at her, but she didn't pay attention. She was used to getting stares from the people who work here, she was nothing like them. They all looked professional in the monochromatic colours, while she was in a pair of washed out cut-offs that practically showed her ass, and a cropped yellow tank-top that came to just below her breast. She was showing a lot more skin than she would normally (unless she was on the beach), but this heat was nothing to be messed with.

She smiled once she saw her Whackadoodle and she pushed the sunglasses that were covering her eyes, to the top of her head, "Sheldon!"

She saw him lock eyes onto her, and the intensity of his gaze. It made her already heated body feel even worse, the fine hairs on her arms and the back of her neck standing to attention. (_Why was he looking at me like that?_) She watched him walk towards her, and she suddenly felt very vulnerable sitting on the hood of her car. She hopped off when he reached her, and she quickly noticed just how tall he was. She looked up at him unnerved to see him already looking down at her. His eyes were so _blue_.

"Why…why were you so late?"

He was silent for a moment before he looked away from her, "Work got me caught up," he said as he smoothly walked to the passenger side of her car.

She followed him quietly, getting into the driver side she started to pull out from his assigned parking spot. She didn't know what just happened, but she felt like something did. She refused to think too much about it though because she was sure she didn't want to open that can of worms. The mystery that was Sheldon Cooper was now Amy's problem, she wouldn't stick her nose where she wasn't needed. But then she started thinking about Amy, why hadn't he gone home with her? She knew Amy offered multiple times for him to go home with her, but he always rejected it and said she would come get him instead. She used to think it was out of practicality, they did live in the same apartment. But now, as she glanced down at his hands, she wasn't too sure.

He held onto the arm rests of his seat so tightly, his knuckles were turning white. She hadn't realized just how large his hands were, they spanned the width of the arm rest easily and she found herself wondering about the appendage further. (_How did he touch Amy? Did he even touch Amy?_)

His voice broke her out of her thoughts, "You should really start wearing more clothing when you come outside," his voice was clipped.

She felt anger start to boil through her veins. If he felt like he was going to start telling her how to dress and what she should be wearing, he had another thing coming. She didn't go through a multitude of jerk ex-boyfriends just to have her neighbor start trying to control her. She'd very much rather him go back to his quiet weird self, opposed to trying to tell her how she should be dressed. "And why is that, Sheldon?" She forced herself not to snap.

He glanced at her, and his eyes were so _blue_ she felt herself getting lost, "Because, too many people look at you."

She didn't know what that meant, and she refused to ask. A loud horn honking pulled her out of her thoughts, and she focused on the road. So maybe she shouldn't be angry at him, but she also wasn't sure what she _should_ be. Like she said, she wasn't going to open that can of worms.

* * *

"It's about time you guys arrived, I was beginning to think I should send a search time out for you guys," Leonard said dramatically as he dropped the pizza on the coffee table, "The pizza was starting to get cold, so you might have to microwave it, Sheldon," he said in a tone that said he didn't really care.

Penny fell onto the chair by the door, her head hanging backwards, "Sorry. Mad scientist was late, and then traffic was a killer," she said, "I'm loving this AC by the way, it is way too hot outside," she groaned as she used her hand to fan her face. She could feel eyes on her, and she ignored them, it wasn't anything new by this point.

However, instead of three pairs of eyes on her she felt four. She fought against her gut, and she looked up; Howard, of course, Raj, and Leonard, yes. She looked towards the kitchen and saw the taller man staring at her unashamedly, her mind was screaming at her, telling her to look away, but she couldn't. She was enthralled by this _different_ Sheldon, what was he thinking? What was he doing? She exhaled softly when she saw his tongue dart out and lick his bottom lip. Subconsciously, she felt herself do the same thing; she watched his eyes darken and narrow, the water bottle clenched mercilessly in his fist crinkled as his grip tightened, and she found herself wondering what it would feel like to feel his hands grip her tightly. Her breathing sped up, and she knew he noticed, his eyes leisurely trailed down her body, her chest, her stomach, her legs, and back up, slowing at her heaving chest. She saw the smirk on his face.

Their moment was broken instantly, when the door opened.

"Sorry I'm late you guys, traffic was terrible," Amy apologized as she walked through the door to 4A. It was like somebody hit 'play', and everyone went back into actions. Leonard continued looking for a suitable show, Raj and Howard carried on with their conversation, while Sheldon continued rummaging through the fridge and Penny busied herself on her phone. She didn't know why she felt guilty; she didn't do anything with Sheldon. They shared a weird moment, and she didn't know what she could categorize it as, but they didn't touch so it wasn't betrayal.

She decided from then she wouldn't pay much attention to Sheldon for the night. He had to be just coming to terms with his sexuality, and he probably discovered he couldn't repress his urges forever and he needed a release. She was probably just the first female he laid eyes on for the day, but now that Amy was here, he'd be all over her. As he should be.

Amy sat beside Sheldon in the middle seat, and as she walked by everyone Penny caught the heavy scented perfume her friend was wearing. (_Maybe they already had sex?_)

She couldn't help but watch the couple from the corner of her eye. Sheldon regarded Amy as normal, pleasantries.

Amy moved closer to Sheldon, during their lunch hour she had slipped more of the serum into his water and he drained the cup easily, he _should_ be bursting at the seams with sexual desire. No Homo Novus could resist the amount of serum she put into his body. His vomeronasal senses would be in overdrive and he should be struggling to hold himself back from attacking her. She predicted at this level his senses were being attacked by her scent, and he would be able to _feel_ her move the slightest bit, hyperaware of all of her moves.

She could barely keep her giddiness in. She just might be sleeping with her boyfriend before the week was up.

She watched him from the corner of her eye, he was stoic, and his face was emotionless. The only thing she could notice was the slight furrow of his eyebrow and the way he was clenching his khaki pants in his fist so tightly she was sure he was about to rip a hole in them. She grinned and leaned over to whisper to him, "You know, you don't have to hold back," she informed him. He jumped slightly at her closeness, "What?" He replied.

She nodded to his tense hands, "You don't have to hold back."

He immediately let go of his pants and glanced at her, then back to the TV, "I don't know what you're talking about, Amy, but I rather not know. I'm not holding anything back," he said simply.

Amy frowned deeply, why wasn't he letting his urges come over him? He couldn't possibly be that strong. He should be lusting after her right now, completely and utterly devoted to her and lost _in her_. She huffed and looked at the television, not paying attention to whatever was on the screen. She was lost in her thoughts, confused as to why her experiment was failing. Whenever she gave the serum to her monkey's they went at it for hours, almost immediately. She'd give it to the male monkey, and he became a possessive, territorial, alpha male over his female counterpart. That should be Sheldon by now, he should be possessing her.

If he didn't start giving into his urges then there could be negative side effects, and honestly, she didn't know what those were. Her monkeys always gave in, and never had to experience the negative side effects of the serum, she just hoped she could get Sheldon to do the same. She chanced a glance at her stubborn boyfriend and saw him staring intensely at their blonde friend who sat across the living room from them by the front door, currently swiping furiously on her cellphone, clearly, she wasn't paying attention to the television either. She narrowed her eyes, Penny was extremely knowledgeable when it came to everything Sheldon related, maybe she could get some advice from her Bestie.

Meanwhile, Penny was just thinking about how much she needed to get laid.

She hadn't gone on a date since she and Leonard broke up a year ago, and from then she had one one-night-stand. She knew Leonard felt great about it, he believed it was because she was incapable of moving on from him, but it was just her being in a dry spell. She had hung around her boys for so long she looked for the tall smart guys instead of the muscular ones now, and the tall smart guys didn't really go to clubs on Friday nights. So, it wasn't easy to find them.

She pulled out her phone and swiped to a folder on her iPhone she never used, _Online Dating_, she looked over her shoulder to see if anyone was watching her and then opened the long-forgotten _Tinder_ app she had downloaded once in a time of desperation. She sighed silently, this was so demeaning, was she really this desperate? She felt the intensity of Sheldon's gaze on her neck, and decided yes, she was that desperate. She started swiping through the profiles until she found one she liked. It wasn't long until she heard her phone beep, indicating she had a match.

After a few minutes, she let out an unexpected squeal and everyone turned their heads to look at her in surprise. She looked at them sheepishly, "Sorry," she apologized.

"What was that all about?" Leonard questioned.

She smiled happily, her white teeth gleaming in the darkness of the room, "Nothing, nothing…" she waved them off, not wanting to get into details about what she had just done. She didn't want anyone thinking she was desperate, even though at this moment she was. She just didn't want them to know.

"Clearly it wasn't nothing, Bestie, share with us. I'd love to be excited with you, isn't that what Besties do?" Amy questioned.

The blonde sighed deeply, "I just got a date, that's all."

There was a sudden vibration going through the room, and she knew she wasn't the only one who had heard it because everyone turned their heads, but no one could pinpoint the source of the deep quick noise. It wasn't until everyone turned away she realized it was Sheldon who had let out a deep growl. She felt her stomach knot at the implication.

"A date?" Leonard's voice was small, "With who?"

She was annoyed that clearly everyone was much more interest in her love life than the show on the screen. She waved them off, "No one important, just some guy Brandon Beckerman or something," she knew saying his name would get a reaction because he happened to be the son of the man who was the CEO of AEG, the company that owned one of the most famous sports center in the world, the Staples Center. His family was rich, and held a lot of steam in Los Angeles, Penny didn't know how she got so lucky matching with him, but she wasn't going to let the moment pass.

She predicted right when the guys gawked in surprise, Amy was confused, but Raj quickly explained the situation and she too was surprised at the luck Penny had. The blonde knew she should be happy about what was about to transpire for her, but a part of her couldn't ignore the burning feeling her skin felt as she tried to disregard the intense look Sheldon was giving her. His cobalt eyes burning into her skin so deeply, she swore she was naked under his eye.

She let out a quiet breath, and she swore (she did) she saw him smirk. And it scared her, because she knew how to read people, she knew how to read people extremely well. And the look on his face, the smirk on his lips it all read one thing: _Challenge accepted._


	3. III

**III.**

Penny smiled at her reflection, she thought she looked pretty damn good actually. She'd been out of the game for almost a year, it was time to start getting back out there. Her biological clock was ticking, and it wasn't planning to slow down any time soon. This guy seemed like he was sensible, they had a few conversations through _Tinder,_ and he had even called her, they didn't have a whole lot in common, but it was a lot easier to follow a conversation with him than one of her boys. Besides, he was cute. Sandy brown hair, grey eyes. He was taller than Leonard, but shorter than Sheldon (that's how she measured guys heights now), and he wasn't overly buff. It was a plus that he happened to be loaded, but that wasn't a big factor.

She hoped the night went well.

She knew his family was very formal and fancy, and she knew she wanted to make a great first impression. So, she took out a yellow summer dress. It was short sleeved, and had a boat neckline, it cinched her waist and then the skirt flowed out to her knees in a circle that swished around her legs when she turned. She paired it with sandy wedge heels and let her hair out in a loose wave that reached her mid-back. She felt pretty, and it's been a long time since she felt like that.

She looked at the clock on the stove and saw that he would be arriving soon. She did her final touch ups and let her nerves calm down. She didn't know why she was so nervous, she's had dates before, so this was nothing different. But the more she thought about it the more it felt like she was going on this date to prove something to herself, or to someone. She didn't have much time to think about it though because there was a knock on her door, and it wasn't in the regular tune she was used to hearing it.

She let out a breath and spat her gum out in the trash by the door. She opened it with a smile, "Brandon?"

The grey-eyed man smiled widely, "Wow, you're…you're even more beautiful than your pictures," he said in genuine awe.

Before she could reply, the door to 4A was whipped open and she closed her eyes in annoyance. She should've known better than to stop and exchange pleasantries with her date at her door, she knew just one of the boys had to be watching from the peep hole. What she didn't expect was to see all four of them standing there, with different looks on their faces. Raj looked happy, he was always happy for her and she loved him for that, Howard looked like he was ready to shoot Brandon a whole list of questions, she knew he was always a fan of sports but didn't speak about it because the rest of the guys didn't share that sentiment, so standing in front of the guy whose father owned one of the biggest stadiums in the world, it must've been something special for him. Meanwhile, Leonard looked like he was ready to shoot Brandon with a laser or something he had back at the lab, the jealousy was radiating off him.

The one who surprised her the most was Sheldon, he out in the hallway, leaning against the doorframe, one leg propped up as he had his arms folded across his chest. One eyebrow was raised while his eyes glowed a deep fire. His gaze was so intense, she felt like she was doing something wrong just by standing here with Brandon. Though, that couldn't be possible.

Brandon hooked a finger over his shoulder at the guys in 4A, "Protective brothers?" he teased.

She rolled her eyes, "That would've been easier to explain, wouldn't it," she murmured and took his hand in her own, she didn't miss the glance Sheldon gave their interlocked fingers, "Brandon, this is the guys; Raj, Howard, Leonard, and Sheldon," she introduced them, "They're my friends."

Leonard was first to stick his hand out, "I'm actually her ex, ex of many intense months," he reintroduced himself, "I told her I love her," he added for affect. Brandon just nodded his head, he didn't seem put off and Penny silently thanked whoever was listening, "I'm sure you did," Brandon smirked.

"I'm such a fan of you and your family, your father is a legend in my books," Howard gushed, "Such a smart man! That investment was iconic," he rambled on. Raj clapped a hand on his friends back and guided him back into the apartment after smiling politely at Brandon.

"And you?" Brandon asked, interested in the quiet tall man sizing him up and down.

Penny was surprised to find Sheldon had been sizing Brandon up and down, his gaze grew cloudy, and she saw the veins in his arms as he clenched and unclenched his fists, but she couldn't think as to why he felt this way. This was a side of Sheldon she wasn't used to, and it scared her. Yesterday, that moment they shared was weird, and intense, and steamy, and so many more words synonymous to sexy, but it couldn't have really happened because she would never betray Amy that way.

The silence was deafening, and she started doubting that Sheldon would introduce himself, so she started to speak but Sheldon quickly pushed himself off the wall and was suddenly standing ten toes to Brandon, he looked down at the brown haired man, and spoke in a voice she hadn't heard before, "Dr. Sheldon Cooper," he introduced himself.

She didn't understand why but hearing him say his own name in the tone he used, it sent a fire into her core and she had to turn her head away from the men quickly, afraid they'd see her blushing. She watched with embarrassment in her eyes, as Brandon held a hand out to the taller man, he would soon realize in an awkward way, that Sheldon Cooper didn't shake ha—

She was surprised when Sheldon gripped Brandon's hand with a firm hold. He shook it twice before forcing Brandon to let go. He smirked as he leaned back up against the wall, his cool demeanor not breaking. She knew she wasn't delusional, and she knew she wasn't the only one confused with this act he was putting forth because she noticed the confused look on Leonard's face too. He only shook his head and walked back into the apartment, refusing to believe he just saw Sheldon shake a stranger's hand.

"So, you're taking my Penny out on a date, Brandon?"

She almost didn't catch the _my_, because it flowed from his mouth so easily and quickly that it sounded normal. She did witness the odd look on Brandon's face though and decided that it was time to break up the conversation before it got any weirder. She stepped between the two men, sure that it would soon turn into a weird piss contest because she didn't know why or _how_, for that matter, but Sheldon was radiating pure Alpha male right now and she had to get herself away from that before he completely destroyed her date.

"I think it's time to go, Brandon. You've met the banes of my existence, so that's that," she said trying to rush him away, it was then she realized she left her purse in her apartment, not having enough time to grab it because the guys whipped open their door. She sighed, "Just start the car, I'm going to grab my purse really quick."

Brandon glanced once more at Sheldon, and then nodded his head with a smile, he kissed Penny's cheek and made his way down the stairs. Penny smiled at his retreating figure and then quickly moved towards her apartment. Unaware that Sheldon had still been watching them the entire time, unaware of the way his fists clenched and jaw tensed at the way Brandon kissed her cheek and let it linger, unaware of the way he followed her into her apartment, unaware of the fact he _locked_ the door behind him, and extremely unaware of the fact he was now standing a few feet behind her in her bedroom, swinging her purse on his finger tauntingly.

She grumbled to herself quietly, annoyed she couldn't find her purse, (_I swear it was on my bed_). She threw some clothes around haphazardly; aware she was starting to make a terrible first impression on Brandon. She turned around, threatening to just leave the damn thing, she didn't need it anyways (except she did). She was surprised when she saw Sheldon standing behind her, her bag dangling off his fingers and his eyes leisurely wandering over her body. She didn't know what happening, but she knew she had to get out of the room before something that both of them regretted happened. She was about to go on a date, and he was dating her best friend, she had to keep reminding herself that.

"Oh, Sheldon," she said trying to ease the tension in the room, "Thanks, I was looking for that," she reached for her purse, but the tall man pulled it away from her grasp easily. However, she overextended, and she ended up falling into him slightly. Her whole face flushed, as she quickly righted herself.

He tilted his head slightly, and walked closer to her, throwing the bag to the side. She watched as it hit her dresser and fell unceremoniously to the ground, she gasped, "Hey! I needed that for tonight," her tone was accusatory, but she didn't know why. What was she even accusing him of?

"Why are you going on a date?" His tone was the same as it was in the hallway, deep, animalistic, and it made her stomach knot. She had to remember this was Sheldon Cooper, schedule to poo, Sheldon Cooper. He shouldn't be making her feel this way. At all.

She squared her shoulders, but avoided eye contact, "Because I can, Sheldon, and quite frankly I don't need your permission. Now, if you and the scooby-doo gang are done interrogating my date, I have a guy to go see," she tried to push past him. But as soon as her bare shoulder touched his arm; it was like something in him changed…snapped.

A sound so primal, she couldn't describe it, escaped his mouth and next thing she knew she was being pinned up against her wall. He was breathing heavily, and she could feel his heart beating through his chest. She was confused, and turned on, but so confused. She looked up into his eyes, they were blazing. His eyes closed as he lowered his head and sniffed her along her collarbone and neck, he inhaled deeply, like he was smelling a freshly plucked rose.

"My Penny…" he drawled, his eyes opening, showing dilated pupils and a fiery gaze.

She shook her head, "No. Sheldon, you're dating Amy…I—"

His hands that were caging her against the wall, fisted and he punched the wall by her head, she jumped slightly. She knew Sheldon wouldn't hurt her, but she didn't know _this_ Sheldon, this wasn't her Sheldon. She chanced touching him, she placed a hand on his arm, and saw him instantly fall into her touch, "Sheldon…" she said softly.

"My…" he trailed off as he laid a kiss on her neck, "Penny…" he reiterated, whispering into her ear as he kissed it.

She tried to push him away, but her resolve was slipping, and (_damn his lips felt so good on her skin_).

He noticed her falling into him, her knees going weak and he smirked against her skin. He raised his head slightly and angled it better, immediately placing his lips against her own. The kiss was fervent and passionate, as if they were afraid to pull away from each other. His large hands spanned her lower back, pulling her roughly against his body and she gasped at the feeling of his erection pressing against her stomach. Sheldon took advantage of her opened mouth and his tongue immediately started to explore her mouth, eager to taste her. He groaned in pleasure, feeling her tongue reciprocate.

Her hands tangled in his hair, and she felt like close wasn't _close enough_ and she hated feeling like she needed him to breathe.

The shrill noise of her cellphone broke her out of her reverie, and she immediately pulled away from him. Only succeeding because he was taken off guard. She saw the glare on his face, the hurt and the rejection, but she couldn't think about that because he didn't get to be hurt. He had just kissed her, and now they were cheaters. Well, she wasn't, but she betrayed her friend and it was just as bad. She looked away from him, and picked up her bag, "I gotta go…" was all she said before she ran out of her bedroom. All she heard was the angry shout of Sheldon, and something being broken.

She didn't know what was wrong with him, but this wasn't right, he wasn't _right_. Sheldon didn't act like this; he didn't act without considering all possibilities. Sheldon wasn't smoldering, he wasn't spontaneous. Sheldon didn't make her weak in the knees, and make her heart skip a few beats. Sheldon didn't make her forget how to breathe, nor did Sheldon make her appreciate the colour blue so much more. Maybe she needed to spend some time away from him?

She smiled when she saw Brandon still waiting for her, maybe this would be a great thing for her…maybe Brandon would want to get away with her for the weekend?


	4. IV

**IV. **

She was pissed.

She tried everything to get him to notice her, she started to dress provocatively, (knee length skirts and sweaters that weren't turtle necks), and she even complimented his equations a lot more, (even though she felt her science was far superior). She knew about the male ego, and she felt if she stroked his than he would let her stroke something else. She was wrong. He was absolutely ignoring her.

All weekend he seemed angry and unresponsive, like his mind was somewhere else. He wasn't receptive to her compliments or her seduction, she didn't know what she was doing wrong.

She hypothesized that by now, the fourth day on the serum, he would be _dying_ to get near her and touch her. It should be _physically hurting_ him to not be able to touch her, but when she came around, he didn't even give her more than a glance and a nod. She did notice some changes in him, however, like he barely spoke to them anymore. He spent most of his time at the white board, and he was hesitant with his routines. He didn't really follow his rules anymore, not until Leonard or someone pointed out what he was doing was going against his schedule, then he would correct himself. She did know that it was working though, because Leonard made a comment about him always leaving to take cold showers.

It just got her angry that he was _still_ refusing to touch her. Was she that repulsive?

So, they all sat in the living room of 4A, spent from their game paintball and the heat beating down on them. She was a placeholder until Penny got back from her trip with her new boyfriend, Brandon. They went away for the weekend to some lake his family owned. Leonard was radiating jealousy at the information, she was surprised to see Sheldon's jaw tense at the announcement too, but he quickly recovered. She supposed he didn't like Brandon that much; he was probably on his enemies list.

"So, what are we supposed to do now? It's too hot to do much of anything," Howard groaned from his seat.

Raj nodded in agreement, "When I left India, I thought I'd be getting away from the intense heat."

Just then the door to 4A opened, and a head of blonde hair entered the apartment, "Hey guys!"

Everyone sprang up in surprise, Penny stood there with a large smile on her face. Her skin glowing from her recent tan, and her golden hair was falling down her shoulders in loose beach waves. Leonard was clearly happy to see her, almost jumping up out of his seat to greet her with a hug and a large smile on his own face. Howard and Raj gave her a quick group hug, saying hello. Amy waved, refusing to get up from her spot beside Sheldon, because if she did who knows if she'd be able to sit there again. She knew this was Penny's spot.

What surprised most of them was the fact Sheldon was standing to his feet instantly and crossing over to her with a smirk on his face. (_Since when did Sheldon smirk? And why was he __**now**__ happy?_) Amy refused to acknowledge her gut feeling, because that was her Bestie and nothing like that could ever happen. And besides, she had a boyfriend. She let herself relax slightly, reassuring herself she was just over thinking. However, her mind revisited the thought when she noticed Sheldon pulling Penny into a tight embrace, resting his chin on her head, sniffing her hair slightly.

She looked away from the pair, "Penny," she broke them apart, "Do you want to have a girl's night tonight? With Bernadette and everything?"

Penny smiled and moved away from Sheldon, "Sure! That sounds great."

Amy took note of how Sheldon's eyes followed Penny predatorily everywhere she walked. She felt the beginnings of a monster starting to grow in her gut, and this monster happened to be green.

"Girls night? Since Penny is back, I was hoping we could all do something together," Leonard's whiny voice broke through.

Amy looked at Leonard curiously, "Leonard, Penny is spoken for. It is rather sleazy to pine after someone who's already in a relationship," she stated simply, hoping her own boyfriend would hear the message. But that hope was lost when she saw him following Penny into the kitchen, a few steps behind. She saw Leonard roll his eyes and they went back to the TV.

The television was loud, and she couldn't hear what was being said in the kitchen all she could see was Sheldon standing with his back to the living room, and Penny on the other side of the island facing him but Sheldon's tall stature blocked her easily. She frowned deeply. Maybe this serum wasn't a good idea after all?

"What Sheldon?"

She noticed he was slightly surprised by her stern tone, but he recovered quickly. His arms unfolded from his chest and he braced himself on the edge of the island counter. His eyes were burning into her own, and she felt like he was reading her soul and her emotions, but she refused to look away.

She had gone away for the weekend with Brandon, and it was amazing. They went to a lake house his family owned, and his parents had come too. She was nervous at first, but after meeting them she realized she really liked his family. She felt like she could actually blend in well with them. She was nervous because of her lack of education, but his parents only looked at her like a normal person and not someone that was beneath them. It put her nerves at ease, and she was capable of relaxing all weekend with minimal thoughts of her tall scientist neighbor. Now, she was back, and he was right under her nose again. As soon as she entered the door to 4A she could feel his eyes on her. It made her body feel hot, and she felt her heart pounding in her chest.

She ignored it. She had to. Amy was sitting a few feet in front of them. She refused to break her friendship for a fleeting lust he felt for her. She was hoping this weekend would make him come to his senses, he didn't like her, and he didn't want her. She wasn't _his_. From the look in his eyes, the feeling had only intensified, and honestly, she was afraid to be alone with him. The last moment they shared had been so intense, she wasn't capable of focusing on her date with Brandon, she blamed it on nerves and embarrassment. Brandon just laughed and told her it was ok, he really liked her. She couldn't help but think, (_and I really like Sheldon_). She didn't know where it came from, but she knew if he got her alone again this time, she might not even stop him.

She officially wanted him. But she was trying so hard to pull away from him and her feelings because of Amy, and honestly in part because of Leonard. He'd be crushed.

"How was your little vacation?"

The smirk on his face unnerved her. It was like he felt like no matter who she dated she would always be his, and she'd always come back to him and it pissed her off because she didn't belong to anybody. Much less her best friends' boyfriend. So, she tried to kick him in his ego.

"It was amazing. Brandon's parents were there, and they loved me, they were practically begging me to marry him," she added nonchalantly, as she moved about the counter, keeping an eye on his reaction as she moved. She saw his grip on the edge of the counter tighten, and his knuckles turn white. His jaw tensed, and he tilted his head slightly as if trying to figure her out.

"Well you're not marrying him."

It was a statement, and she sensed his confidence when he said it and it only fuelled her anger, because it sounded like Leonard and she didn't dump Leonard only to be controlled by her neighbor, "You don't own me, Sheldon," his eyes turned to slits and the blue of his eyes darkened to almost a black, "I can do what I want with who I want. And if I want to marry Brandon, I will," she hissed at him, ignoring the way he inched towards her with every word she said.

She was mindful that her friends were still in the living room, a few feet away, so she stepped back giving them space.

"Go to your apartment."

She was confused at his instruction, and she knew it wouldn't be wise to follow it but something in his eyes told her he was serious and if she didn't, she'd probably regret it. She glared at him and turned on her heel, leaving 4A despite Leonard's protests.

"Where are you guys going?" She heard him ask Sheldon, she wasn't too sure what he replied but soon enough her door was being closed and she could hear the chain link being placed on the door. She felt a chill run through her at the knowledge no one would be able to get in even if they had a key.

She didn't say a word, because she wasn't going to let how she felt be known to him. Sheldon was like a predator right now, and she wasn't sure how to deal with this version of him, so she was going to let him speak. However, before she could do anything, she felt him step up behind her and grab her arm, effectively spinning her around to face him.

She felt his grip on her arms tighten, drawing her tighter to his body, his lips crushing hers. She whimpered at the feeling of his body pressed up against hers, and she felt her arms circle his neck and her fingers bury themselves in his hair. He deepened the kiss, nibbling on her bottom lip forcing her mouth open, and his tongue immediately started exploring every crevice of her mouth. She moaned and he swallowed the sound, it fueling him to continue touching her.

He bent slowly and picked her up, wrapping her legs around him, he walked them into her bedroom and dropped her onto her mattress. He quickly began taking his shirt off, needing to feel her skin on his, needing to show her that she wasn't going to marry Brandon because she was _his_. His eyes never left hers as he unbuttoned his pants and then hovered over her, depositing kisses all over her exposed skin. Sucking on her neck softly, and nipping at the sensitive flesh.

Her entire body felt like it was set on fire, and her skin was tingling with life as he kissed all over her body. She couldn't form a coherent thought, and she was filled with need and want. She let him rip her shirt off her body, her breast freely bouncing in his face. His eyes roamed over her body hungrily, she instinctively moved to cover her chest, embarrassed she had exposed herself to her neighbor. He grunted and gripped both of her wrists in one hand, forcing them above her head and pinning them to the mattress.

He bent his head and took one erect nipple into his mouth, sucking on it, and flicking it with his tongue. Her moans sounding like music to his ears. He pressed himself against her core and hissed at the feeling of his erection pressing against her, the friction too much. He quickly worked his pants off, needing to feel her.

"Sheldon," she panted, "Amy…"

He growled, honest to god growled, "No."

In a weird way, she understood what he meant. She wanted this too, she wanted this so damn bad she didn't care that Amy's feelings would be hurt. But the morally sound side of her wanted to stop, wanted them to pull their pants up and walk away before they couldn't take back their actions. She threw her head back into her mattress, her moral compass severely broken.

She let him rip her shorts off her body, her thong no match for Sheldon's primal state.

"Look at me," he ordered, both of them completely naked. She opened her eyes and saw him staring down into her face, she felt him move and suddenly he was pushing himself inside of her. They both made noise of pleasure, it was a year since she last had sex and Sheldon was stretching her to fit. Her eyes rolled to the back of her head, and she gripped onto his back as he began thrusting into her with fervor, the intense pounding on her headboard was sure to upset her neighbors. Neither cared about the fact their friends in 4A could hear them if they were at the door, all they cared about was the way he felt buried inside of her.

He grabbed her legs and threw them over his shoulder, needing to go deeper.

She moaned loudly once he thrusted into her, feeling him hit places that once went undiscovered. He let her wrists go, and swiftly turned her onto her stomach, propping her ass up in the air he began thrusting again. Her ass bouncing back against him, meeting his thrusts half way. He groaned as he let his hands get tangled in her hair and tug on it. "Fuck," he swore and if Penny could get any wetter, she was dripping, "My Penny…" he groaned.

"Say it," he ordered as he tugged her hair harder.

She moaned, "I'm yours, Sheldon," she half begged, egging him on to move faster. She was going to cum, and she wanted him to do it with her. He looked down at their joined bodies, and felt his dick twitching inside of her. He flipped her back onto her back, and gripped her headboard, steadying himself as he began moving inside of her at an alarming rate, not caring about the noise they were making nor the sweat that was coming off both of their bodies.

His groans got louder as he felt himself reaching his climax, "Fuck, Penny," he nearly shouted, "I'm going to cum," he said and she nodded, wrapping her legs around his waist as she felt her climax coming. Her body arched as she gripped her sheets, her orgasm wracking her body as she milked his dick. She felt him tense and then a warmth overcame her as she felt him emptying himself deep within her, still riding out his orgasm with slight thrusts.

After a few moments, he pulled out of her with an audible _pop!_ and it was only then she took in the extremity of what they have done. Not only did he cheat on Amy, she cheated on Brandon.

She felt him roll over beside her, collecting her in his arms protectively, tucking her under his chin, and she pushed him away, guilt gnawing at her. "Sheldon…"

He knew the tone she was using, and his eyes narrowed, "No."

She rolled off the bed quickly, collecting their clothes in a rush. She felt him advancing on her, and she didn't care, she just needed him out so she could collect herself. She was supposed to be having a girl's night tonight and she didn't need this. She felt him grip her waist, slowing her movements, "Penny…"

"No, Sheldon. You have to go. What we did was wrong, a mistake."

He glared at her, obviously hurt, he shoved her up against her dresser and saw her wince at the movement. "You can't leave me."

"I'm not with you, Sheldon. I'm dating Brandon you're—"

"No!" He shouted, his face turning red, "No! You're not with Brandon. You're mine, you're mine!" His eyes were stormy, and for the first time in her life she was terrified of Sheldon Cooper.

Her voice was quiet, "You have to go."

He quickly spun away from her, grabbing his clothes from her hand and hastily putting them on, "This wasn't a mistake. You're mine, I made you mine," he kept muttering over and over, not once looking back at her.

She was confused. She didn't know what was going on with him, but she knew it couldn't happen again. She watched as he stormed out of her room and soon after she heard her door slam close. She wrapped her arms around her body and let her tears fall. She was just as guilty, she told him she wanted this, she let him do this. She couldn't even blame him if she wanted to. Only, she was the one who saw how wrong it was. It didn't even seem like he cared. All he wanted was her, and anyway he was capable of getting her.

She had to do what was right. She pulled out her cellphone and dialed Brandon's number.


	5. V

**V.**

Amy felt defeated.

No matter how many numbers she crunched, or how many times she went over the serum she saw no flaws. There was absolutely nothing wrong with her serum, or her math. It should be working, and it should've already made him hungry for her. Then, she saw the way he was watching Penny, and she felt sick to her stomach. What if all this time she was trying to get him to be attracted to her with her serum, and it wasn't her that was the problem? What if the serum actually did work, but she wasn't the target of his affection and lust? What if it was her Bestie?

It made her sad. Once again, she lost in life. But then she remembered it wasn't Penny's fault, she was the one who administered the serum to Sheldon without his knowledge or consent. So maybe she deserved all of this, maybe this was karma working against her? She picked up the glass of wine in front of her and threw it back, it gave her a slight burning taste in her throat, but she once again thought she deserved it. It had been a few days since she last gave him another dose, and she refused to give him anymore. With what she already gave him, he would be dying for sexual release, and he wouldn't be sedated until he got what he needed. Clearly, it wasn't her either.

She looked at the two blonde women sitting beside her, how would she even bring it up though? Penny was extremely protective of the guys; she just might go junior rodeo on her. She winced at the thought of being hogtied by Penny. Hopefully, Bernadette would help.

"Ladies…" she started, gaining their attention, "I have something to say."

She didn't realize the faraway look Penny had on her face, or if she did, she didn't acknowledge it. Everyone had their own demons.

Bernadette touched her hand encouragingly, "We're all ears, Amy."

Sighing, she placed her empty glass on Penny's coffee table. All she wanted was to have a group of female friends, and now that she had it, she didn't want to lose them. But she knew she had to talk to somebody about what she did to Sheldon, and she couldn't talk to the guys because they would only go back to him and tell him what she did. Then, he would terminate their relationship. And although she knew what she did was grounds for termination, she didn't want him to leave her. She was happy, and she was perfectly content knowing he was attracted to somebody else.

"I…I did something."

"What did you do, Ames?"

She looked at them sadly, "Have you noticed a difference in Sheldon lately?"

Penny's breath hitched, and Bernadette just nodded her head, "Yeah. I was meaning to ask you why he's so quiet all of a sudden, and really tense," she then looked at Penny, "You weren't here, but that whole weekend you were gone with Brandon, he was so angry, he barely spoke or even left his whiteboard. Everything just set him off."

Hearing that effected Amy negatively. It just further proved her point that her boyfriend was attracted to his neighbor, but the more she thought about it the more she realized it was inevitable. They had a bond that no one could ever come in between. Whoever Penny or Sheldon married, would be doomed to a loveless marriage because both only had eyes for each other, although they didn't know it.

"I was so tired of not being loved by him, and not being touched," she looked down, "At work I was working on this…this serum for my monkey's, get them mating because they wouldn't do it anymore. Their sex drive was just…gone," she looked up at them both, realization hitting Bernadette, and Penny still looked confused.

"You didn't, Amy?" Bernadette said slowly.

Amy nodded. Penny shook her head, "Didn't what?"

"I…I used it on Sheldon, Penny. I used my sex serum on Sheldon, and it's altered him terribly."

"What…what does that mean?" She felt like her head was spinning.

Amy exhaled, ready to explain in detail what that meant for Sheldon, "What the serum does is enhance the male libido. Basically, you send out pheromones to the people that are attracted to you. The serum enhances the senses in these people, and your pheromones become strong. It takes over all of their senses, every waking moment they spend is filled with you. The need to have you becomes strong, and they can't control it. It becomes a ravenous need to have you. In their eyes, you are theirs and no one else's. It worked for my monkey's, they mate like rats now, so I thought it would work for Sheldon and me. I am his girlfriend, so he should become so attracted to me that we don't leave the bed."

Penny's eyes narrowed, "So what determines who he's attracted to?"

She shrugged, "Well, that's on him really. The serum only brings out his true feelings tenfold. And I dosed him three times, so it's a lot stronger than my monkey's—"

"Wait, aren't monkey's polygamous animals?" Bernadette interrupted.

Amy nodded, "Yes. But I altered the serum so that didn't happen. When I inject Ricky, he only has eyes for his partner. That's his life partner from the moment they mate," she looked at Penny, "And that's what happened to Sheldon. He's basically an animal right now, and the person he's attracted to…" she trailed off, "The person he's attracted to is basically a steak and he's a lion, and in his mind that steak is his and he'll do anything necessary to get to that steak."

"So why…why are you telling us this? Can't you deal with it? Isn't this what you wanted? Doesn't this mean you and Sheldon have been having sex?" Penny couldn't help the questions that left her guilty mouth.

She shook her head, "No. Sheldon has been repulsed by me since I started dosing him. He won't even look at me. Which means the target of his affection is someone else, and until that person gives him what he needs he'll only get worse."

"Get worse?" Bernadette asked quietly.

"Yes. His body is succumbing to his baser urges, he's primal right now, and the longer he holds off from taking care of his needs the stronger the needs get. He'll end up hurting himself or somebody else. Sheldon is stubborn, and the fact that I know he's in his room right now, and not trying to deal with his urges with who he's attracted to…it tells me he's holding himself back. The more he does that the worse he'll get."

There was an uneasy pause, none of the girls wanting to ask what Amy meant.

So, Amy sighed again, "I know I'm his girlfriend, and I know he'd be cheating on me…but he needs to deal with this before it's too late. He needs sex."

"What if…" Penny flinched, "What if he already had sex?"

Amy looked at Penny sharply. She wanted to push her on that question, but decided she had no right.

"Well, _if_ he did have sex already and he's still like this then it wasn't enough. He needs it until he gets it out of his system."

Bernadette spoke up this time, "I think what you did was completely unorthodox and wrong, Amy. It's disgusting that you used him as a test subject in your need to get laid," she said with her nose in the air.

Amy nodded, "Yes. I know, and I agree. I feel awful."

"Then you know what _you_ need to do. You need to tell him the truth, and let your consequences come."

The brunette looked at the door to 4B, uncertain. "He's been the only guy who was interested in me, I don't know if I'm ready to let that go."

"Well clearly he wasn't really interested in you, if he's not here trying to rip your clothes off," Penny put her hands over her mouth after she realized what she just blurted out, "I'm sorry Ames."

She shook her head, "No. You're right. I have to tell him; I'll tell him tonight."

"Good. Now how are you going to find the girl he's attracted to?" Bernadette asked.

Amy looked at Penny and then back at Bernadette, "She knows already."


	6. VI

**VI.**

"I'm so sorry, Sheldon, please don't leave me."

He was furious, don't leave her? She _drugged_ him! He wasn't some lab rat, or one of her monkey's that she could just dose with drugs whenever she saw fit. What she did was unethical, illegal, and down right rude! He had the right mind to get her fired, and incarcerated. He glared at her from the threshold of his bedroom, "Don't leave you? Amy, I know your judgement must have lapsed since you drugged me, but surely you do understand that _this_ gives me great cause to leave you!" He said viciously, "And I am. I don't trust you at all to be near my person, and that isn't a great foundation for a relationship. Clearly you aren't satisfied with me either, so let's call this what it is, and leave."

Amy frowned deeply, "Or is it because I'm not blonde and my name isn't Penny?"

He felt his teeth bare at the sound of her name, and his blood started to pump quicker. All of a sudden, he could _smell _her, even though she was across the hall and there was no way he could actually smell her. He could _feel_ her, and _taste_ her, and he _needed_ her. He fidgeted and his grip tightened on his door, "Leave, Amy."

She noticed the difference in his body, and her heart broke slightly. She didn't want to believe her Bestie and boyfriend…well, ex-boyfriend, were involved with each other, but the way she saw him react at just the mention of her name she knew she deserved this. She did do this to herself, her life and her relationship were fine before she decided to drug him. Yes, the relationship was slow-moving, but she was fine living in blissful ignorance to her friends' feelings. But now, now it was the only thing she could think about.

"Penny knows."

She saw his knuckles turn white, "She knows I drugged you. She knows the only way to save you from yourself is to have sex with you until the need is out of your system. I also know you guys had sex once already," she looked up at him, "It's all over your face, whenever I mention her name you get so tense. I wish you looked at me like that."

He didn't speak. Too afraid to trust his own voice. She only sighed and nodded her head, "Goodbye, Sheldon."

* * *

He was glad Leonard had taken the weekend to be with Leslie Winkle, despite how much he hated the harpy he needed to be alone for a while. He didn't trust himself enough to leave the apartment because he knew the moment he stepped out into the hallway, he'd _smell_ her, and he would break down the damn door just to get to her. But he didn't want to hurt her, he didn't want to ruin their friendship more than he already had. Just the thought of being inside of her again was enough for him to tighten his fists, his short nails digging so deep into his skin it started drawing blood.

He tried everything he could to prevent himself from forcing himself into her apartment. Cold showers were the start of it, and it started to work, but shortly after it stopped, and he realizes it's probably because Amy had dosed him again, and the serum got even stronger. He was reduced to self-pleasure, and it wasn't easy to do it knowing his roommate was just a wall away, but he had to. His mind was being consumed by her, and he needed a release. And it worked. Until he had sex with her, now nothing was enough. He wanted more, he _needed_ more. But he couldn't do it, because she was dating Brandon, and she was his friend.

He scowled at the thought of her boyfriend. He wanted nothing more than to keep her in her apartment, tied up, and prevent her from going on her date that night he came to pick her up. He knew he couldn't do that though, so he settled on giving her a mind-numbing kiss, and he knew it worked because much to his chagrin she was going on a romantic getaway with him to his family's lake house, and it ruined his entire weekend. He couldn't see her, touch her, smell her, it was like she was gone, and he hated it. He was angry all weekend, and he didn't want to see any of his friends. She was his, and she was gone.

He closed his eyes tightly, his erection straining against his pants. He groaned as he let a large hand rub against it over his pants. He couldn't masturbate, it would only make his desires worse. But it was like his mind had another idea, and his hand started snaking into his pants, gripping his hardened length in a closed fist, stroking it as his mind went to places that smelled of apple. Her chest, and her ass, her lips, _oh god her lips_, and the wondrous things that they did to him. His hand moved quicker, and his breaths got ragged.

"Fuck, Penny."

He could _feel her_, and he could _smell her_. His eyes shot open once he heard the door to 4A open, and his hand let go of his erection that was standing boldly on display. She was in his apartment, and his body was on alert at how she was slowly approaching his bedroom. He heard her soft knock.

"Sheldon?"

"Go away, Penny."

It hurt him to say it, but he needed her to go. He was holding himself back from opening his door and having his way with her. He quickly zipped up his pants and backed up to the corner of his room. He heard her let out a breath and start to twist his door knob.

"Penny, no!" He roared a lot louder than he thought he could, and he heard her gasp and the door stop.

But then it opened widely, she stood there in nothing but a flimsy tank top and shorts, and he had to grip the edge of his desk because she _had_ to know what she was doing to him and it wasn't fair, because he was trying so damn hard to be the good guy but whatever Amy put in his body was telling him –yelling at him, _take her! Make her yours! She is yours! Take her now!_ His throat produced a low growling noise and he felt his penis standing painfully.

"Sheldon…I know," she said softly. Her voice did nothing to help the matter.

He shook his head, "I don't want to hurt you, Penny, please, leave."

"You won't hurt me, Sheldon. I…I want this. I want to help you."

He watched as she slowly started to remove her shirt, "Please, let me help you, Sheldon. I don't want to see you in pain anymore," she threw the shirt over her head and to the ground. His eyes never once left her own and she felt like it was best she held his eye contact, that way she would be prepared for whatever movement he made.

She reached behind her and closed his door, locking it in the process.

His Adams apple bobbed as he swallowed heavily, "Penny, you don't understand what's wrong with me."

"I do, Sweetie, in human speak you're just extremely horny right now."

"I'm _craving_ you, Penny," his eyes burned deeply into her own, trying to convey exactly how he felt towards her, a part of him trying to scare her away, "Every part of my body is burning for you, and it won't be sedated until I have you beneath me, withering and screaming my name," he closed his eyes and exhaled, a small smirk playing on his lips, "I could hear it when I close my eyes," he looked at her again, "I hear you screaming my name, and I can feel your nails in my back, your legs around my waist," he stepped closer to her experimentally, "I can _smell_ you," he stated.

Penny felt her knees begin to weaken just at the sound of his voice. Never did she think Sheldon Cooper of all people would talk dirty to her, and it was doing wonders to her arousal.

"Then, then let's do it," she hooked her fingers around her shorts and pulled them down. His breath hitched in his throat, noticing she hadn't been wearing underwear or a bra. His normally blue eyes turned dark, and his drawl came out as he spoke in a husky voice, "Penny, are you sure? What about Brandon?" He growled his name.

She frowned, her eyes looking towards the ground, "I called him after that night we had," she sighed, "I never cheated on anybody, and I felt so fucking terrible Sheldon," she looked at him, "I never blamed you. I know I played an equal part in this, and honestly, I don't regret it. But I told him because I felt so guilty. He said he was disappointed but not surprised, he saw the way you were looking at me when he came to get me. He said, he said he knew from the way you were looking at me that he was running a race you already won. He said he knew I was already yours," she looked up at him, "We broke up right after."

"You're single?"

She nodded, and before she could speak, she felt herself being pressed up against. Sheldon had crossed the bedroom, taking her in his arms and was holding her so tightly she was positive she would have bruises. "I want you to understand what you're telling me, do you understand?" it was a warning and she could hear it in his voice.

She locked eyes with him, and only nodded slowly, "I understand."

Everything else moved in a blur.

All she felt was Sheldon, _all_ of him. She didn't know what she expected from him or having sex with him, but it wasn't romantic. It was primal. One moment she was pressed up against his door, and the next she was on her back, breathing heavily as he pushed himself inside of her.

She could feel him inside of her stomach as he lifted her legs and pushed into her deeper. She moaned as she gripped the sheets on his bed and her head lolled back, she arched her back and wrapped her legs around his waist "Fuck Sheldon!" The only thing that could be heard was the sound of their skin connecting, and the loudness of her moans.

Her body felt alive, and her skin felt like it was on fire. She felt herself getting lost in him, and only a small part of her couldn't wrap her mind around the fact she was having sex with her crazy neighbor, but the pleasure was too much, and she didn't dare stop him.

He buried his face into her neck, his thrusts not slowing, and she felt him licking and sucking on her neck unapologetically. She knew there would be a large vibrant mark there when he was done, but she didn't care. She knew he was marking her. In his mind, she was good as his and that was the end of it. She found she didn't mind that at all. Something inside of her tingled at the thought of belonging to Sheldon Cooper.

She cried out as he pushed into her at an angle, and she felt his moves becoming erratic. She knew he was about to cum, and she tightened her grip on his back and desperately tried to keep up with his pace, as he buried himself into her and let himself come undone.

She breathed heavily, attempting to catch her breath, she let her legs close, "Wow."

She didn't know what she expected after having sex with him, but it wasn't to hear him growl in her ear, to feel him peeling her legs open, and to feel his hardened length against her sensitive core again. She gasped when she felt him pushing into her again.

That's when she remembered Amy said he needed to get it out of his system. That could last all night.

And it did.

* * *

The change was almost instant, and it scared her slightly. Sheldon had gone from primitive primate to anal physicist within a blink of an eye, and now she sat on the side of his bed knees weakened, heart racing, and hair a mess, not to mention awkwardly – she didn't know what to do or say, and he wasn't saying anything either.

"I—I'm going to go," she stood to her feet, wrapping his white sheet around her body, in attempt to keep whatever modesty she had left. She looked down at her feet, her clothes were shredded, and she couldn't even attempt to put them back on. Somewhere in between the fourth and fifth round, she said she had to go to the bathroom and tried to put her clothes back on, but he ripped them off of her and told her to go naked. She obliged. She regretted that now, because she would have to do the walk of shame wrapped in a sheet.

She sighed, "I'm glad I could help you out, Sheldon. Don't worry, I won't mention this again."

She moved to the door but stopped once she felt his eyes shift towards her, "Penny."

She didn't know why she stopped or even what she expected, but she listened with her heart in her throat.

"I don't want you to leave."

She looked at him.

"I know for the past week and few days I've been under a drug induced state, and parts of my brain were being used at large…but, I was always somehow aware of what was going on," he looked away, "No. I couldn't control myself, despite how hard I tried. Especially when manhandling you, I really am sorry for that, but I did know how I felt and how real it was. In a way that serum helped me do and say things I wouldn't have said otherwise."

"What are you saying, Sheldon?"

He looked at her, "I don't know if this meant anything to you, Penny. I don't know if the last seven hours meant anything to you, but I know for me the last seven hours meant everything. It was my first-time having sex," he exhaled, "And though a lot of it was under the influence, I remember it, and I remember the way you made me feel, and the way _I made you feel_. And…and, I want to feel it again," he took her hand tentatively, "I want to make _you_ feel it again."

She was shocked.

"I know I won't be the way I was a few days ago, I won't be like the meathead guys you date. I'm not like them, but I do suppose some underlying part of me always considered you mine, and I know you're not a piece of property and I know I don't own you. But I feel like on my heart, in a bold pink script is your name, and I don't want to get rid of it."

She didn't know she was crying until a tear hit her arm, but she felt herself nodding.

"This meant everything to me too, Sheldon. I feel the same way. I have for some time now, but I didn't think you would ever feel the same."

He just chuckled, "I wouldn't tolerate you so, if I didn't feel the same way."

She dropped the sheets in the process of walking over to him, and saw him blushing, "It's nothing you haven't seen before," she teased as she hugged him tightly. Their naked bodies pressing against each other. She felt him tentatively place his arms around her, and she exhaled deeply, content.

"I guess we should thank Amy."

"Why, Sweetie?"

"For the experiment she performed on me, it brought us together."

She shook her head slightly, "Maybe not. It'll be too early for her to accept us being together, we don't want to push it in her face."

He nodded in agreement, "I agree," he looked down at her, "In the meantime can we try kissing again?"

She grinned and leaned up to him, kissing him deeply.

* * *

**This is the last chapter! But after reading over some of my stories, I realized this story could fit as the prologue to my two shot Anything Could Happen. So look at that, full circle! **


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